The present disclosure relates generally to a transmission device for translating a linear driving motion into a rotary output motion. More particularly, the present disclosure relates to a transmission device for use with an adjuster of a vehicle seat, and to a ratchet-type seat adjuster equipped therewith.
A transmission device of the generic type for adjusting the inclination of the backrest of a vehicle seat is disclosed by the published patent application DE 30 01 164 A1. The disclosed transmission device comprises a simple lever mechanism by means of which the movement of a linearly acting piston of a hydraulic cylinder is translated into a rotary motion. The output torque in the disclosed transmission device remains substantially constant over the entire travel of the piston. Transmission devices of this type take up a considerable amount of space and are less suitable when torques of different magnitude and different rotational speeds are required during the course of the rotary motion.
To facilitate the release of a locking detent device (e.g., a ratchet-type seat adjuster, etc.), a high release torque is often required in order to rotate the locking components out of direct engagement. However, the same relatively high torque is often not necessary during adjustment of the locking detent device. Once the locking components are out of engagement, the components are to be rapidly brought into their release limit position, for which a high adjusting torque is no longer required.
Thus, there is a need to provide a transmission device of compact construction for translating a linear driving motion into a rotary output motion. Further still, there is a need to provide a transmission device for which the output torque and speed are to be easily adjustable over the course of the movement.